1. Field of the Invention
The present invention relates to a floor-level adjusting device for a pool which is capable of adjusting the floor level of a swimming pool and supporting it at the adjusted level so as to make the pool suitable for use with a variety of people ranging from adults to infants.
2. Description of the Prior Art
In recent years, health care has become popular among persons in general and swimming is considered to be one of the most suited sports for health care since everyone, from the aged to infants, can practice swimming, and swimming brings into active play nearly all the muscles of the body. This has resulted in the development of a number of swimming clubs. Today, besides swimming clubs, a variety of schools from kindergartens to universities, hotels and the like are provided with swimming pools. In general, most of the large-sized swimming places include various kinds of pools for exclusive use with adults, children or infants, but a great number of smaller swimming places, respectively, have only a single pool.
Accordingly, for the purpose of making a single pool available for all kinds of people including adults and infants, it is necessary to change the depth of the pool by adjusting the position of the pool floor, that is to raise the pool floor so as to be suitable for children or infants or to lower it for adults.
To achieve this, it has been proposed, as shown in FIG. 20, to dispose a number of supports 4 on the floor 2 of a pool 1, the supports 4 having legs 3 for effectively raising the floor 2 to a level appropriate for infant use while on the other hand, such supports 4 being removable for effectively lowering the floor 2 to a level suitable for adult use. However, this measure has presented a problem in that it is troublesome, inefficient and requires much time to change the floor level. To avoid this problem, a mechanism for changing the floor level under a simple operation has been developed.
Specifically, as illustrated in FIG. 21, the bottom of an existing swimming pool 11 is dug down about 50 cm from an ordinary level so as to provide a support bottom 15 which has a plurality of horizontally extending air feed passages 16 formed therethrough and leading to a source of pressurized air 19 comprising an air compressor, and a number of vertical passages 17 each connected at their lower end with one of the horizontal passages 16 and at their upper end with a lifting means 10 comprising bellows which serves to support a movable floor 18 comprising a drain board. The bellows 10 are supplied with pressurized air by the compressor 19 so that they expand in the vertical direction under the action of the pressurized air fed therein whereby the movable floor 18 is raised from the fixed support bottom 15 to an appropriate level, thus making the depth of water in the pool 11 shallow so as to be suitable for use with children, while on the other hand, by venting or opening the air feed passages 16, air escapes into the atmosphere to allow the bellows 10 to be contracted under their own weight as well as the weight of the movable floor 18 so that the movable floor 18 is lowered to increase the water depth in the pool 11 so as to be suitable for adult use.
mentioned mechanism for solving the above-mentioned problem is shown in FIG. 22. In this mechanism, similar to the first mentioned mechanism, the pool ground is dug out deeply from the normal level about 1 m to form a support floor structure 25 of a swimming pool 21 on which a movable floor 28 is supported for vertical movement by means of a plurality of lifting means 30 each having the form of a fluid cylinder. The fluid cylinders 30 are fed with operating fluid such as air or hydraulic oil through fluid passages 26 in the fixed floor structure 25, the fluid passages 26 being connected at one end to the fluid cylinders 30 and at their other end thereof to a source of fluid pressure (19). The movable floor 28 is caused to move in the vertical direction under the action of the fluid cylinders 30 so as to change the depth of water above the movable floor 28 in the pool 21.
In the above-mentioned mechanisms, however, to provide the means for moving the movable, floor in the vertical direction, it is necessary to dig up the existing pool and reconstruct it, thus involving a problem in that the pool is not usable during the period of the reconstruction.
In particular, for the purpose of utilizing the pool as a playground with the movable floor of the pool being raised and held flush with the top surfaces of the pool side walls, the above-mentioned lifting means must have a large vertical stroke so that the mechanical strength or rigidity of the pool floor tends to be reduced. For improving the mechanical strength, it is necessary to increase the number and/or size of the lifting means employed, thus resulting in a substantial increase in the construction cost. In addition, when bellows or air cylinder are employed as the lifting means, the adjusted level of the movable floor is liable to be unstable when subjected to heavy loads such as a great number of persons standing thereon since air used as an operating medium is compressible. On the other hand, in when the lifting means comprises a plurality of hydraulic cylinders, there may be a risk of oil leakage which would contaminate the water in the pool.